Re: [PATCH v2] netfilter: nf_tables: add hash expression

[Laura Garcia <nevola@gmail.com>]

On Wed, Aug 10, 2016 at 10:38:08AM +0800, Liping Zhang wrote:
> Hi Laura,
> 
> 2016-08-10 2:22 GMT+08:00 Laura Garcia Liebana <nevola@gmail.com>:
> > This patch adds a new hash expression, this provides jhash support but
> > this can be extended to support for other hash functions.
> >
> > The modulus and seed already comes embedded into this new expression.
> >
> > Use case example:
> > meta mark set hash ip saddr mod 10
> >
> > +static int nft_hash_init(const struct nft_ctx *ctx,
> > +                        const struct nft_expr *expr,
> > +                        const struct nlattr * const tb[])
> > +{
> > +       struct nft_hash *priv = nft_expr_priv(expr);
> > +       u32 len;
> > +
> > +       if (!tb[NFTA_HASH_SREG] ||
> > +           !tb[NFTA_HASH_DREG] ||
> > +           !tb[NFTA_HASH_LEN])
> > +               return -EINVAL;
> 
> I think tb[NFTA_HASH_MODULUS] and tb[NFTA_HASH_SEED] should also be
> checked is NULL or not? :)
> 

tb[NFTA_HASH_MODULUS] is not optional now so we can check it here, but
tb[NFTA_HASH_SEED] is optional so we can check and if it's null, then
assign 0 to the seed value.

> > +
> > +       priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]);
> > +       priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]);
> 
> Should we use nft_validate_register_load and
> nft_validate_register_store here to check the validity ?
> 

Yes, I'll include that.

Thank you Liping.